![]() A command can be sent from multiple points in the code but is consumed by a single endpoint, consumer or command handler. They are named in the imperative such asĬommands can be validated and rejected by a command handler if they are invalid. ![]() Commands are instructions to perform some action. We should, perhaps, take a moment here to talk about the two types of messages we use in a message driven system. MassTransit layer an actual messaging layer on top of either RabbitMQ or Azure Service Bus which means that is provides for serialization and routing. Comparing the two is beyond the scope of this article but there are some good articles on that already. For large installations I’d recommend building more tightly on top of cloud based transports, but that’s a topic for another blog post. In my mind the cost of NServiceBus is well worth it for small and medium installations. There is, of course, a cost to running NServiceBus as it is a commercial product. NServiceBus is perhaps the most well know option. NET space which can be layered on top of raw queues. There are a couple of good options in the. Wiring would be very painful on a large scale. Nobody wants to do that for any sort of sizable application. We had to do our own wiring and even our own serialization. We did it directly with RabbitMQ which was a bit of a pain. To setup logging there is another method we can use on the HostBuilder.In the last post, we created an application which can send tasks to a background processor. Loggingįinally, there is one more cross-cutting concern for which we can use the generic host to do setup: logging. Now we can set the connection string to RabbitMq inside our appsettings.json, and possibly override its value for a particular environment by adding an for example. Var host = cfg.Host( new Uri(configuration.GetConnectionString( "RabbitMq")), h => Var configuration = serviceProvider.GetRequiredService() ConfigureAppConfiguration((hostContext, config) =>Ĭonfig.SetBasePath(Environment.CurrentDirectory) Ĭonfig.AddJsonFile( "appsettings.json", optional: false) Ĭonfig.AddJsonFile( $"appsettings.json", optional: true) To setup configuration we can use ConfigureHostConfiguration and ConfigureAppConfiguration. So far we’ve only used the dependency injection features of the generic host. When we shut down the host with Control-C, the generic host will automatically call StopAsync on our hosted service, which again will call StopAsync on the IBusControl instance which will do some clean up. By doing this, the generic host will automatically run StartAsync on our hosted service, which in turn will call StartAsync on the IBusControl instance, essentially opening the connection to RabbitMq and starts listening for messages. Next, we add our MassTransitHostedService as a scoped service to the DI container as well. ![]() In this case we’re adding IBusControl as a singleton and use MassTransit’s RabbitMq transport as the implementation. ![]() Note that we’re using the ConfigureServices() method on the HostBuilder to add additional services to the dependency injection container. Var host = cfg.Host( new Uri( "rabbitmq://localhost"), h => ConfigureServices((hostContext, services) => ![]() Public static async Task Main( string args) So let’s create a new console application: For example a background processing service that reads messages from a queue and processes them. Creating a console hostĪ typical example of where the hosting API would be useful is in a console application that just needs to keep running until someone stops it. It is currently planned for the 2.1 release and although there is no preview available for that version, we can still try it out which is what I’ve done lately and I’ll go over it in this post. You can read more about the reasoning behind it in this GitHub issue. In fact, the ASP.NET team has seen this as well and decided to further abstract the WebHostBuilder into a more generic HostBuilder API. If we look at that list, there are a few things that are very specific to web applications, but there are also a number of things that are desirable for any type of application.
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